US2696923A

US2696923A - Combined elevator and tail gate for trucks

Info

Publication number: US2696923A
Application number: US141755A
Authority: US
Inventors: Kirwan Y Messick
Original assignee: FRANK G CAMPBELL
Current assignee: FRANK G CAMPBELL
Priority date: 1950-02-01
Filing date: 1950-02-01
Publication date: 1954-12-14
Anticipated expiration: 1971-12-14

Description

Dec. 14, 1954 K. Y. MESSICK 2,696,923

COMBINED ELEVATOR AND TAIL GATE FOR TRUCKS Filed Feb. 1, 1950 3 Sheets-Sheet 1.

INVENTOR Hawaii! Y MES-SICK ATTORNEYS Dec. 14, 1954 K, Y. MESSICK 2,696,923

COMBINED ELEVATOR AND TAIL GATE FOR TRUCKS Filed Feb. 1, 1950 5 Sheets-Sheet 2 INVENTOR HAWAN Y lflsssicz ATTORNEYS I Dec. 14, 1954 K Y, MESSICK 2,696,923

COMBINED ELEVATOR AND TAIL GATE FOR TRUCKS Filed Feb. 1, 1950 I 4 5 Shets-Sheet :5

all hm?! I (387 Il/I/lII/ll/Il/Kl/ll/l/l/fi/ ll/[II/Il/l/l/l/ Ill/ll/Il/ll/ INVENTOR. K12 WHN lfissslcx and tail-gate forming mechanism for trucks.

United States Patent O COlVIBlNED ELEVATOR AND TAIL GATE FOR TRUCKS Kirwau Y. Messick, Arlington County, Va., assignor of one-fourth to Frank G. Campbell, Arlington County, Va.

Application February 1, 1950, Serial No. 141,755

11 Claims. (Cl. 214-77) This invention relates to a combined load-elevating A principal object of the invention is to eliminate the excessive weight which has been a characteristic of many of the devices proposed to serve the purpose of my invention.

A further object of the invention is to provide a loadlifting and tail-gate forming platform and improved mechanism for actuating the same, all of which is built into a simple and complete unit, assembled at the factory, and comprising means for mounting it upon a truck without the necessity of drilling holes in the under structure of the truck as has heretofore frequently been required.

The construction, manner of operation and advantages of-the invention will be best understood by reference to the accompanying drawings, wherein:

Figure 1 is a side elevation of the device of the invention showing the parts in lowered position and with the platform, or gate, in section,

Figure 2 is a like view showing the parts in the position that they occupy when the platform has been lifted to truck floor level, but with the platform still in its loadsupporting position,

Figure 3 is a fragmentaryview showing some of the elements of Figure 2, and showing the platform moved to vertical, or tail-gate forming position,

Figure 4 is a rear elevation of the hangers and their connecting tie rods which are secured to the frame members of the truck, and which serve to pivotally connect the swinging arms and links hereinafter described, to the elevating platform.

Figure 5 is a plan view of the elements of the invention,

Figure 6 is a diagrammatic view, illustrating the motor, pump, hydraulic cylinders, fluid supply lines, and the control valves therefor, hereinafter described,

Figure 7 is an enlarged sectional view through one of the telescopic'links which holds the platform horizontal during the time that it is being moved from the position of Figure l to the position of Figure 2.

Like numerals designate corresponding parts in all of the figures of the drawings. The particular embodiment of the invention which I have chosen for purposes of illustration comprises a pair of hangers, each hanger comprising a pair of plates 5 and 6, said plates being welded or otherwise secured upon the end portions of a transverse torque tube 7. This tube not only serves the function of tying the hanger-constituting plates to each other, but it is so welded to the outer plates 6 that said plates close the ends of the tube, and thus said tube is adapted to serve as a reservoir for the oil, or other fluid,

which is used in the hydraulic system by which the platform is elevated. The tube 7 and the plates 5 have welded thereto a pair of saddles 8, and these saddles have openings formed therethrough at 9, for the passage of tie rods 11). The upper ends of these tie rods pass through plates 11 which rest upon the top of channels 12, these channels representing a part of the chassis of the truck to which the device is to be applied. One of theplates 5 also serves as a mounting for arotary or piston type.

pump 13 and a direct connected motor 14 by which the pump is driven. The intake of the pump is indicated at 15, leading from tube 7 to the pump and the dis charge line of thepump is indicated at 16 and leads to 3 two cylinders.

2,696,923 Patented Dec. 14, 1954

pivot pins

17, 18 and 19. The

pivot pins

17 and 19 extend only from plate to plate, but the pivot pins 18 are extended outwardly beyond the plate 6, as indicated at 18a. The load-lifting platform 20 may be formed in many different ways. As shown in Figure 1, it comprises a solid metal top plate 21, an outer-edge angle strip 22, and the torque tube 23 which stiffens it and which extends throughout its length. A plurality of braces 24 of U shape extend from the torque tube to the angle strip 22. Heel plates 26 welded to top plate 21, and to the torque tube 23 carry the

pivot pins

27 and 28, pins 28 lying below the pins 27. Stout box-like arms 29 are pivotally connected at their outer ends to the pins 27, and are pivotally connected at their inner ends to the pins 17 of the hanger plates. The arms 29 are closed box-like members in cross section, and they are relatively wide at their rear ends and taper toward their outer ends. By making these arms closed, as stated, they are adapted to house the hydraulic cylinders and their piston rods, indicated at 30 and 31. The piston rods 31 slide in and out of the cylinders in the operation of the device, and they are highly polished to secure the necessary close fit to adapt them to retain the high pressures employed in hydraulic lifts. By thus housing these members in the. arms 29, they are protected from.mechan1cal damage,

20 in its horizontal position throughout the time that it' is being lifted from the ground level position to the floor level position of the truck. During this elevating movement of the platform, the rods 34 are bottomed in the sleeves 33. That is to say, the links have then assumed the position in which they are as short as they ever get. This is the position shown in Figure 7. When in this position, lines through

pivots

27, 28, 18, 17, and back to 27 constitute parallelograms. However, stout springs 35 surround the rods 34, and when load is on platform 20, said springs are strongly compressed between the lower ends of the sleeves 33 and collars 36, by which the links are pivoted on pins 18a. As long as there is a load upon platform '20, the relative position of the parts will be that indicated in Figure 2, but when the load has been moved from platform 20 over into the body of the truck, the platform may be manually swung upon pivots 27 to the position illustrated in Figure 3, where, as before stated, it constitutes a tail-gate closure for the truck. This upward movement of platform 20 is rendered possible by the fact that the link constituted by sleeve 33 and rod 34 is an extensible one, and further the springs 35 act to thrust the platform 20 to the vertical position of Figure 3, as described. The springs also act to cushion the movement of the tail-gate back to theposition of Figure 2. It requires but a very slight eflfort upon the part of the truck driver to close the tail-gate when it is assisted in its closing movement by the powerfully compressed springs 35. However, the strength of the spring is such that the weight of the tail-gate will keep it from tipping upwardly above the horizontal, until manually assisted. The gate may be provided with a conventional latch to hold it in the position of Figure 3, if desired,

but the springs render such a latch unnecessary.

Referring now to the diagrammatic Figure 6, it will 'be seen that the fluid pressure line 16 leads to one or more of the hydraulic cylinders 30. This is to indicate that a hydraulic cylinder may be used upon only one side of the structure where light work is to be done. However, a better balanced structure is had by using The motor 14 may be driven from the conventional truck battery b, or a separate battery may be provided. A

circuit including wires

37 and 38, push button switch 39, and relay '40, provides means, when the switch 39 is closed, to set the motor and pump in v operation. This pumps oil from the oil reservoir 7 into the discharge lines 16. This in turn causes the pistons to move out of their cylinders and to act upon the pins 32 to lift the platform to the position of Figure 2. Removing the finger from push button 39 causes the motor to instantly stop. A check valve 41 holds the pressure in the line and holds the gate in its elevated position as long as may be desired. When it is desired to return the platform to the position of Figure l for the reception of an additional load, a push button switch 4-2 is pressed. This completes the circuit from the positive side of the battery through switch 32, 42, wire 43, a normally closed solenoid valve 44, and to the negative side of the battery at 45. This opens the solenoid valve and permits the oil to drain out of the lines 16 back into the oil reservoir 7, whereupon the weight of the platform causes it to descend.

It will be observed that the whole assembly including the hangers, the pump, motor, fluid supply lines, platform and the actuating arms and the links, are all ca. ried by the torque tube 7, and thus may be assembled at the factory and placed in position upon a truck by the mere application of the tie rods or bolts 10. This, as before stated, avoids the necessity of a great deal of laborious work made necessary where the truck frame has to be drilled to receive special fittings.

The structure herein disclosed is an extremely strong and rigid one, and yet, considering the results achieved, it is very light in comparison with the structures here tofore proposed. This mechanism will lift more load, pound for pound, in comparison with its own weight than any with which I am familiar, and that by a very large margin.

The provision of the arms 29 of closed box-like formation, and making these arms enough deeper adjacent their heel portions so that they may be tied together by the transverse torque tube 29a, renders this part of the device very rigid and capable of resisting the torsional strains which are brought upon the structure when a heavy load is placed nearer one end of the platform 20 than the other. Also, the use of the torque tube 23 in the gate itself renders that structure very rigid and strong in proportion to its weight. It will be understood that the torque tube 290 is welded at its opposite ends to the inner side walls of the arms 29.

An important feature of the invention resides in the manner in which I have related the outwardly thrusting pistons 31 to closed top, box-like arms 29. The points of thrust between 19 and 32 is such that the pistons thrust upwardly. This is much better than having the piston pull its arms upwardly because the construction that I have devised leaves the arms 29 wholly closed, thus protecting the cylinders and pistons from the weather, and making the use of cam slots in the arms unnecessary. This permits the complete housing of the cylinder by the box-like arms and protects the piston rods from mechanical damage as well as from damage by the elements. Attention is directed to the fact that the torque tube 2%, not only unites the arms 29, but it does this at a point spaced away from the pivots 17 and toward the outer ends of arms 29. This makes for great rigidity with light weight. The use of a tube instead of a bar of equal diameter makes for li ht weight, and yet the points of attachment of the tube to the arms is over a diameter equal to that which would be presented by a solid rod, or bar, of equal diameter. This spacing of the points of attachment of tube to arms, and the spacing of the tube away from the pivot points of the arms, gives a structure of great strength and rigidity. While I have shown the torque tubes as being circular in cross section, they may be other than circular, if desired. In the platform, the torque tube stitfens and strengthens the gate to resist the torsional strains when the gate is unevenly loaded. The torque tube 7 mounts the hangers, motor, pump, and all other parts of my attachment, on so rigid a foundation that twisting strains in the truck body will have no effect whatever upon this unit. Also, it mounts all parts of the invention directly at the rear of the truck where they are readily accessible. No parts extend forwardly under the truck to inaccessible places.

It is to be understood that the invention is not limited to the particular construction shown, but that it includes within its purview whatever changes fairly come Within either the terms or the spirit of the appended claims.

Having described my invention, what I claim is:

1. In a combined elevating platform and tail gate for vehicles, a pair of hollow box-like arms wider at their inner than at their outer ends, a load carrying platform having vertically spaced pivots at its inner end portion, means pivoting the inner ends of the box-like arms to a truck body, means pivoting the outer ends of said arms upon the upper pivots of the platform and a large diameter torque tube extending between and rigidly uniting the inner side walls of the said arms at a point rearwardly of the fore and aft center of said arms but at a point spaced from the rear ends of said arms.

2. A structure of the character described, comprising a load lifting platform, a pair of arms pivoted at their outer ends to said platform and at their inner ends to a truck body, a pair of telescopic links pivotally connected at their outer ends to the platform, and at their inner ends to the truck body, said links, when in their shortest position, constituting with said arms, parallelograms by which the platform is held substantially hor izontal while being lifted from ground level to truck fioor level, springs associated with said links which are compressed during the lifting of the platform, and which tend to tip the platform upwardly to tail-gate forming position when the load is removed from the platform at truck floor level, said extensible links comprising rods, and sleeves in which said rods slide, the springs surrounding the rods and engaging the inner ends of the sleeves, said rods being bottomed in said sleeves when the links are in their shortest and parallelogram forming position.

3. In a device of the character described, the combination of a load lifting platform, a pair of arms, the outer ends of which are pivotally connected with the platform and the inner ends of which are pivotally connected to a truck body, said arms being of closed boxlike formation, hydraulic cylinders and pistons housed within said box-like arms and acting to thrust the outer portion of said arms upwardly when pressure fluid is admitted to the cylinders, and a torque tube extending between said arms and rigidly aflixed to the inner side walls of said box-like arms, at a point materially in advance of the rear ends of said arms.

4. In a device of the character described, the combination of a load lifting platform, a pair of arms, the outer ends of which are pivotally connected with the platform and the inner ends of which are pivotally connected to a truck body, said arms being of closed boxlike formation, hydraulic cylinders and pistons housed within said box-like arms and pivotally connected to the truck body and said arms at points to cause them to act to thrust the outer portion of said arms upwardly When pressure fluid is admitted to the cylinders, a pair of telescopic links, the outer ends of which are pivotally connected to said platform and the inner ends of which are pivotally connected to the truck, means carried by the said links comprising springs tending to extend them and tending to tip the platform upwardly upon its pivotal connection with the said arms, said links comprising rods, and sleeves which slide upon said rods; said links, when in their shortest position being ofsuch length as to constitute with said arms parallelograms which maintain the platform horizontal during its lifting movement.

5. A structure of the character described, comprising a load lifting platform, a pair of arms pivotally connected at their outer ends to the heel of said platform, and a hydraulic cylinder and piston housed in one of said arms and pivotally connected to the arm and to a truck carried part and acting to thrust the arm upwardly from a point below said arm, said arms being of hollow, box-like formation and being materially wider at their inner than at their outer portions, and a rigid torque tube uniting the inner sides of said arms at points materially spaced from the inner ends thereof.

6. A unit for mounting a hydraulically actuated lift gate on a truck, comprising a transversely arranged torque tube with hangers at the outer ends thereof, said tube being closed to constitute a reservoir, pivots carried by said hangers, an electric motor and pump driven by said motor mounted to be moved bodily with said tube and to be positioned by the securing of the tube to a truck body, andmeans for securing the tube to a truck body.

7. A lift gate for trucks, comprising a torque tube, a plurality of rearwardly extending braces secured to the torque tube, a plurality f forwardly extending heel plates secured to the torqu: tube and carrying pivots and a top plat eextending across the heel plates, torque tube and said braces, and a member extending throughout the length of the gate to which the rear ends of the braces and the rear portion of the top plate are secured.

8. In a hydraulic power lift for trucks, a pair of supporting brackets attached to the truck body, one at each side of said body and at the rear end thereof, each of said brackets carrying three pivots, spaced throughout the height of the brackets, a load lifting platform provided at each side with a pair of pivots at its heel portion one above the other, a pair of arms pivoted at their outer ends to the uppermost of said pivots and pivoted at their inner ends to the uppermost truck carried pivots, a pair of links pivoted at their inner ends to the intermediate ones of the truck carried pivots and pivoted at their outer ends to the lowermost pivots at the heel of said platform and forming with said arms parallelograms, a pair of hydraulic cylinders and pistons, said pistons being pivoted on the lowermost truck carried pivots and the pistons being pivoted to said arms at a point nearer the outer ends of said arms than to the inner end thereof, the disposition of the pivots being such that when pressure fluid is admitted to the cylinders the thrust is from beneath said arms, upwardly.

9. A structure as recited in claim 8 wherein the links comprise telescopic rods and sleeves and springs associated therewith compressible under the load lifting action, the parts of said links being of such dimensions that when the springs are fully compressed the effective length of the links is such as to cause them to constitute with said arms parallelograms, said springs tending to further extend the links to tip the platform upwardly at'the conclusion of the lifting operation.

10. A structure of the character described, comprising a load lifting platform having an upper and a lower pivot point at its inner end portion, a pair of upper and lower truck carried pivots, a load lifting arm pivoted at its inner end to the upper truck carried pivot and at its outer end to the upper platform carried pivot, hydraulic means acting to swing the arm and platform upwardly from the pivoted inner end of said arm, an extensible link pivoted at its inner end to the lower truck carried pivot and at its outer end to the lower platform carried pivot, said points being so located and the length of the link and arm being such, that when the link is in its shortest position, it constitutes with said arm the sides of a parallelogram, and a spring carried by said extensible link and so disposed as to be placed in energy storing position as the parts of the link move to the shortest position of said link, said spring tending to extend said link and to thereby tip the platform upwardly upon its upper pivot point.

11. A structure of the character described comprising a load lifting platform, a pair of lifting arms pivoted at their outer ends to said platform and at their inner ends to truck carried pivots, links pivotally connected at their outer ends to the platform at a point below the pivoted connection between said platform and the lifting arms, and at their inner ends to truck carried pivots, said links when telescoped to their shortest positions constituting with said arms, parallelograms by which the platform is held substantially horizontal while being lifted from ground level to truck floor level, and a compression spring carried bodily by at least one of the extensible links and so related to the link as to be compressed by the telescoping of the link, said spring tending to extend the length of the link and tip the platform upwardly upon its pivotal connections with said arms and to tail gate forming position, when the load is removed from the platform at tail gate forming position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,141,928 Brown June 8, 1915 1,733,988 Barnard Oct. 29, 1929 2,099,998 Berg Nov. 23, 1937 2,121,960 Frink June 28, 1938 2,193,532 Frink Mar. 12, 1940 2,284,661 Joy June 2, 1942 2,298,166 Richards Oct. 6, 1942 2,341,807 Olmstead et al. Feb. 15, 1944 2,350,641 Ruddock June 6, 1944 2,391,813 Wood Dec. 25, 1945 2,469,321 Wood May 3, 1949 2,480,528 Wachter Aug. 30, 1949 2,495,143 Simmonds Jan. 17, 1950 2,512,150 Geren June 20, 1950 2,525,424 Novotney Oct. 10, 1950 2,542,047 Mullin Feb. 20, 1951 2,566,547 Bartlett Sept. 4, 1951 2,576,881 Kern Nov. 27, 1951